GP1138 Posted March 15, 2005 Report Share Posted March 15, 2005 Well I'm at class, trying to figure out why my car is running so hot. My fuel trim (according to the GM Tech 2) is running 100+ counts. My instructor says that's really high. This is at idle. It appears that it's dumping fuel, but my economy hasn't gone down at all. What's a good fuel trim reading (in COUNTS because of OBD 1.5 :x :x :x )? Also, my engine timing was at 25* and my temp gauge was up about halfway between 220 and 260, but the scantool was reading 224*... something's funky here. Could the fuel trim have something to do with the fact that I'm using the 3100 fuel rail and injectors with the 3400 intake and setup? Quote Link to comment Share on other sites More sharing options...
slick Posted March 15, 2005 Report Share Posted March 15, 2005 Could very well be the case. You have more air coming into the engine, therefore the computer is *most likely* compensating that by adding more fuel into the mixture to keep its happy level of the air/fuel ratio. As for the temp guage, your guess is as good as mine. Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted March 15, 2005 Report Share Posted March 15, 2005 well, with the temp gauge deal...it appears to me that the gauges in our cars arent 100% accurate to what the actual ECM temp reads...i've had my car plugged in many times to the Auto X-ray, and the temp on the gauge usually reads higher then the ecm temp...i dunno why that is, but i've actually had customers saying their car was overheating, when in fact...it wasnt...i guess that some neat GM shit...(w-body's are the only cars i've seen this on)...the conclusion i've gotten is that the gauge is acurate to a certain %...like, when it reads 220 on your gauge, the car will be 220, but when it goes up...the gauge goes up higher faster then the actual car temp (basically, the numbers on your gauge are just for a reference, and not 100% accurate)... Quote Link to comment Share on other sites More sharing options...
Canada Posted March 15, 2005 Report Share Posted March 15, 2005 Perfect fuel trim is 128.....+/-10 is within spec. On the newer systems........0% is perfect, +/- 10 is within spec. This applies to both long and short term (the *count* system uses different terms, I forget what they are) fuel trims. Tell your teacher he doesn't know anything. I assume this isn't an ASEP (GM) school.... My car idles at roughly 132-135 counts.....so it is having to fatten the injector pulse width slightly. And I actually have a 3400. The gauge differences, I wouldn't worry about at this point. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted March 15, 2005 Author Report Share Posted March 15, 2005 Perfect fuel trim is 128.....+/-10 is within spec. On the newer systems........0% is perfect, +/- 10 is within spec. This applies to both long and short term (the *count* system uses different terms, I forget what they are) fuel trims. Tell your teacher he doesn't know anything. I assume this isn't an ASEP (GM) school.... My car idles at roughly 132-135 counts.....so it is having to fatten the injector pulse width slightly. And I actually have a 3400. The gauge differences, I wouldn't worry about at this point. Ok, so having ~120-130 counts on both long and short term fuel trim is normal? Both readings were just about the same. And this is a GM certified school. My instructor is James Halderman... and I think the reason he didn't know what you said was because my car is OBD 1.5... he's thinking OBD II terms, and they don't work much with older cars. He knows what he's talking about.. he wrote our textbook. Quote Link to comment Share on other sites More sharing options...
Canada Posted March 15, 2005 Report Share Posted March 15, 2005 Well......if hes an instructor.....then he worked at the dealers back in the day and should remember the old stuff....but whatever. Like I said......128 is 0 adjustment.........+/- 10 is okay. Do you really plan on fixing cars in the future???? Quote Link to comment Share on other sites More sharing options...
HokemBokem Posted March 15, 2005 Report Share Posted March 15, 2005 Do you really plan on fixing cars in the future???? Where did he say that? Quote Link to comment Share on other sites More sharing options...
Canada Posted March 15, 2005 Report Share Posted March 15, 2005 Well......going to a tech school its kinda assumed. I didn't realise he is just getting start.....that was by bad. Quote Link to comment Share on other sites More sharing options...
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